package correct.day13;

import java.util.Scanner;

public class Test3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        char[] s = in.next().toCharArray();

        char maxChar = '0';
        int maxCount = 0;
        int[] hash = new int[26];
        // 找出现次数最多的字符以及次数
        for(int i = 0; i < n; i++)
        {
            char ch = s[i];
            hash[ch - 'a']++;
            if(hash[ch - 'a'] > maxCount)
            {
                maxChar = ch;
                maxCount = hash[ch - 'a'];
            }
        }

        // 判断是否能重排
        if(maxCount > (n + 1) / 2)
        {
            System.out.println("no");
        }
        else
        {
            System.out.println("yes");
            char[] ret = new char[n];
            int i = 0;
            // 重新排列
            // 1. 先处理出现次数最多的字符
            while(maxCount-- != 0)
            {
                ret[i] = maxChar;
                i += 2;
            }
            // 2. 处理剩下的字符
            for(int j = 0; j < 26; j++)
            {
                if(hash[j] != 0 && (char)(j + 'a') != maxChar)
                {
                    while(hash[j]-- != 0)
                    {
                        if(i >= n)
                        {
                            i = 1;
                        }
                        ret[i] = (char)(j + 'a');
                        i += 2;
                    }
                }
            }
            for(int j = 0; j < n; j++)
            {
                System.out.print(ret[j]);
            }
        }
    }
}
